1. Field of the Invention
The present invention relates to a thyristor having internal current gain, and more particularly to a thyristor of that character in which there is a semiconductor body which contains an n-emitter contacted by a cathode, a p-emitter contacted by an anode and two base layers respectively adjacent thereto and therebetween and which has an auxiliary emitter which serves the purpose of internal current gain, the auxiliary emitter being contacted by an auxiliary emitter electrode.
2. Description of the Prior Art
A thyristor of the type generally set forth above is known from the "Thyristorhandbuch" by A. Hoffman and K. Stocker, Verlag Siemens AG, Berlin and Munich, 1965, pp. 27-28. The auxiliary emitter, which is there designated as an interstitial component, is permeated by a current when the thyristor is triggered, the current effecting a rapid and large-surface ignition in the area of the principle emitter. Because of the rapid sequence of the overall trigger operation, a thyristor of this type is suitable for high rise velocities of the load current flowing between the anode and cathode, i.e. it exhibits a high di/dt stability. Due to the auxiliary emitter, which is always more trigger-sensitive than the principle emitter, the stability of the thyristor, on the one hand, is lower than that of a thyristor having the same structure in which no measures for internal current gain are provided. What is thereby meant by stability is the protection of the thyristor against unintentional trigger operations given the occurrence of voltages poled in the forward-conducting direction which, under certain conditions, rise very quickly, i.e. represent a high dU/dt load.